This invention relates generally to transparencies, and more specifically the present invention is directed to transparencies with certain coatings thereover and the use of these transparencies in ink jet printing processes. Thus, in one embodiment, the present invention relates to transparencies comprised of a supporting substrate with certain coatings thereover as illustrated herein, which transparencies are particularly useful in ink jet printing processes. Additionally, in another embodiment of the present invention there are provided papers for ink jet printing, which papers contain thereover the coatings illustrated hereinafter with colloidal silica dispersed therein in, for example, an amount of from about 40 to about 60 percent by weight. Accordingly, the coated paper substrates of the present invention may also be incorporated into electrostatographic imaging processes.
Ink jet printing systems are well known. Thus, for example, there is described in U.S. Pat. No. 3,846,141 a composition for ink jet printing comprised of an aqueous solution of a water soluble dye and a humectant material formed of a mixture of a lower alkoxy triglycol, and at least one other compound selected from the group consisting of a polyethylene glycol, a lower alkyl ether of diethylene glycol, and glycerol. According to the disclosure of this patent, the viscosity of the printing inks is subjected to little variation with use in that water is lost by evaporation during recirculation of the ink composition through the jet printer. Moreover, apparently the humectant system disclosed in this patent substantially prevents or minimizes tip drying of the printing ink in the orifice or nozzle during down time of the printer such as when the printer is rendered inoperative. As further disclosed in the patent, the basic imaging technique in jet printing involves the use of one or more ink jet assemblies connected to a pressurized source of ink. Each individual ink jet includes a very small orifice usually of a diameter of 0.0024 inch, which is energized by magneto restrictive piezoelectric means for the purpose of emitting a continuous stream of uniform droplets of ink at a rate of 33 to 75 kilohertz. This stream of droplets is desirably directed onto the surface of a moving web of, for example, paper and is controlled to form printed characters in response to video signals derived from an electronic character generator and in response to an electrostatic deflection system.
Also, there are disclosed in U.S. Pat. No. 4,279,653 ink jet compositions containing water soluble wetting agents, a water soluble dye and an oxygen absorber. Similarly, U.S. Pat. No. 4,196,007 describes an ink jet printing composition containing an aqueous solution of water soluble dye and a humectant consisting of at least one water soluble unsaturated compound. Other patents disclosing aqueous inks for ink jet printing include U.S. Pat. Nos. 4,101,329; 4,290,072; and 4,299,630.
Ink jet recording methods and ink jet transparencies using the above-mentioned or similar inks are well known. There is disclosed in U.S. Pat. No. 4,446,174 an ink jet recording method for producing a recorded image on an image receiving sheet with aqueous inks, and wherein an ink jet is projected onto an image receiving sheet comprising a surface layer containing a pigment, which surface layer is capable of absorbing a coloring component present in the aqueous ink. Also, there is disclosed in U.S. Pat. No. 4,371,582 an ink jet recording sheet containing a latex polymer, which can provided images having excellent water resistance properties and high image density by jetting them onto an aqueous ink containing a water soluble dye. Similarly, U.S. Pat. No. 4,547,405 describes an ink jet recording sheet comprising a transparent support with a layer comprising 5 to 100 percent by weight of a coalesced block copolymer latex of poly (vinyl alcohol) with polyvinyl(benzyl ammonium chloride), and 0 to 95 percent by weight of a water soluble polymer selected from the group consisting of poly(vinyl alcohol),poly(vinyl pyrrolidone),and copolymers thereof.
Other coatings for ink jet transparencies include blends of carboxylated polymers with poly(alkylene glycol), reference U.S. Pat. No. 4,474,850; blends of poly(vinyl pyrrolidone) with matrix forming polymers such as gelatin; or poly(vinyl alcohol), swellable by water and insoluble at room temperature but soluble at elevated temperatures, reference U.S. Pat. No. 4,503,111; and blends of poly(ethylene oxide) with carboxymethyl cellulose as illustrated in U.S. Pat. No. 4,592,954, the disclosure of which is totally incorporated herein by reference.
Although the transparencies illustrated in the prior art are suitable for their intended purposes, there remains a need for other transparencies with new coatings thereover that are useful in ink jet printing processes, and that will enable the formulation of images with high optical densities. Additionally, there is a need for transparencies with a blend of coatings thereover that are compatible with ink jet compositions, particularly those derivable from ethylene glycol/water components. There is also a need for coated papers that are useful in electrostatographic imaging processes wherein images with excellent resolution and no background deposits are obtained. Another need of the present invention resides in providing transparencies with a blend of coatings that do not block (stick) at, for example, 50 percent relative humidity and at a temperature of 50.degree. C.